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首页> 外文期刊>Physical chemistry chemical physics: PCCP >Host effects on the optically active 4f and 5d levels of Ce~(3+) in garnets
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Host effects on the optically active 4f and 5d levels of Ce~(3+) in garnets

机译：在Garnets中的光学活性4F和5D水平的宿主效应

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摘要

When Ce~(3+) is doped in a garnet, it substitutes for some cations. The effect of the substitution on the optically active 4f and 5d levels of Ce~(3+) can be analyzed in terms of an undistorted substitution followed by a structural relaxation, but, whereas the contribution of the undistorted substitution can be predicted/calculated using the crystallographic structure of the pure garnet, which is at hand, that of the structural relaxation demands the detailed local structure around the Ce~(3+) impurity, which is hard to know. Hence the importance of knowing the role of the undistorted substitution. What we study in this paper is the role of the unrelaxed host effects on the 4f and 5d levels of Ce~(3+)-doped garnets (i.e. the interactions between Ce and the second and more distant neighbors). When they are added to the (previously studied) unrelaxed first-neighbor effects, they give the contributions of the undistorted substitutions. We performed spin-orbit coupling, relativistic, embedded cluster, wave function based ab initio calculations on the (CeO8)~(13-) cluster under the effects of the embedding potentials of 21 selected garnets of Si, Al, and Ga, which have been obtained in this work, using experimental unrelaxed structures of the pure garnets. The calculations reveal that the unrelaxed host effect: (1) produces a red shift of the first 4f → 5d transition and (2) is an important contribution to this transition which plays a very important role in differentiating the values it has in different garnet families. The unrelaxed host effect is found to be responsible for the low value of the first 4f → 5d transition in Ce~(3+)-doped Lu2CaMg2Si3O_(12). It is analyzed in terms of 5d and 4f centroid energy contributions and crystal field splitting contributions in the 21 doped garnets. The effect on the splittings of the 4f and 5d levels is also discussed. The undistorted host approximation is found to give reasonable comparison with experiments, so that it represents a relatively fast way to provide reliable ab initio information on the 4f and 5d levels of Ce~(3+) in garnets.
机译：当CE〜（3+）掺杂在石榴石中时，它替换一些阳离子。替代在光学活性4F和5D水平的Ce〜（3+）上的效果可以根据不朽的取代分析，然后进行结构松弛，但是，可以预测/计算未置换的取代的贡献结构松弛的纯石榴石的晶体结构要求CE〜（3+）杂质周围的详细局部结构，这很难知道。因此，了解未变产替代的作用的重要性。我们在本文中学的研究是未密封的宿主效应对Ce〜（3 +）掺杂的装饰的4F和5D水平的作用（即CE与第二和更远邻居之间的相互作用）。当它们被添加到（先前研究的）未密封的第一邻效应时，它们给出了未变产级别的贡献。我们在Si，Al和Ga的嵌入电位的效果下执行了旋转轨道耦合，相对论，嵌入式集群，基于（CEO8）〜（13-）集群的波函数计算在这项工作中获得，使用纯粹的装饰品的实验未加工结构。计算揭示了未密封的主效应：（1）产生前4F→5D转换的红色移位，（2）是对这种转变的重要贡献，它在区分其在不同的石榴条件中的价值方面起着非常重要的作用。发现未密度的主效应是负责CE〜（3 +） - 掺杂Lu2camg2si3O_（12）中的第一个4F→5d过渡的低值。根据5D和4F质心能量贡献和21个掺杂的装甲中的水晶场分裂贡献分析。还讨论了对4F和5D水平的分裂的影响。发现未置换的主宿主近似是与实验合理的比较，因此它代表了在装载机中的4F和5D水平的CE〜（3+）上提供可靠的AB Initio信息的相对快速的方法。

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